Pressure cooker



H. A. WlLSON vPRESSURE COOKER Jan. 1, 1946.

Filed Nov. 13, 1943 1 Mt "2 1a: ATTORNEYS Patented J m 1, i946 U canHarry A. Wilson, Riemann, N. 5., The

Wilcolatcr @ornpany, Elizabeth, H. in, x

- ration of? Appiicaticn November 13, P943, id name. (or. This inventionrelates to pressure cookers of the type commonly used for domesticcooking and preserving and is concerned more particularly with a novelpressure cooker unit, which includes a heating element and means bywhich the operation of the element can beautomatican'y' controlled tomaintain the pressure inside the cooker within limits during the use ofthe apparatus. The new cooker is safe in operation and of simpleconstruction, and it may be readily cleaned and kept in sanitarycondition by ordinary methods without liability of being damaged.

Pressure cookers for domestic 'use are generally recognized as oiferingnumerous advantages over ordinary cooking utensils, in that their11581361- mits a great saving in time and fuel and also makes possiblethe cooking of foods withoutsuch loss in vitamin content as occurs whenfoods are boiled in water in the usual way. The marketing of suchpressure cookers as now constructed has beensomewhat hampered, however,by the possible hazards incident to theiruse- The development of steampressure within a cooker takes only a short timeand, if the cookingoperation is not closely watched, the pressure may exceed safe workinglimits. The generation of such high pressure in a cooker not providedwith a pressure relief device may cause an explosion releasingsuperheated steam capable of causing serious burns and, even if thecooker is equipped with such a device, the functioning of the devicereleases live steam at considerable pressure and with a loud noise.

The problem of controlling the operation of a pressure cooker to preventthe generation of excessive steam pressure therein is made moredifficult by a number of factors. Any control means employed should belight and compact and it should function properly, regardless of theamount of foodbeing cooked. Also, it should be capable of being appliedto the vessel without the problem, because such switches are bulky and,if such a switch is mounted on the cover and connected to the heatingelement by permanentconnections, the cover is cumbersome to handle andit cannot be cleaned by waterwithout possibleinjury to the switch orconnections. If

the switch is mounted elsewhere on the vessel,

its steam inlet may be clogged by food so that the switch is unreliablein action and ii the switch is mounted apart from the vessel, it must beconnected to the interior thereof by a steam connection, whichinterferes with the washing of the cover after use.

The present invention is directed to the prodetachably in circuit withthe heating element cludes a thermostatic element mounted on the outsideof the cooker, because, in the short time required for the usual cookingoperation, the outside temperature of the vessel is not in fixedrelation to the steam pressure therein but varies with the amount ofcold food in contact with the and the switch is small, compact, and oflight weight and it w permanently mounted on the cover in leakprooffashion. The switch is waterproof, and, since it may be quicklydisconnected from the electrical connections to the heating element, themounting of the switch on the cover in no way interferes with theordinary handling of the cover or with its being immersed in water forcleaning purposes.

In the operation of the new cooker, the protective device shuts oil thecurrent to the heating element'when a safe pressure within the vessel isreached and turns the current on when the pressure falls below a lowerlimit. Whenever the switch functions, it produces a sharp audible clickwhich serves as a signal. .If desired, the cooker may also be providedwith a signal lamp which remains lighted whenever the heating ele-' mentis connectedto receive current.

For a better understanding of the invention, reference may be had to theaccompanying drawing, in which Fig. 1 is a vertical sectional view ofthe new pressure cooker; I

Figs. 2 and 3 are wiring diagrams that may be used; and v Fig. 4 is avertical sectional view on an enlarged scale of the pressure switchemployed.

The cooker illustrated in Fig. 1 comprises a pot it, which may be of anysuitable form, and a base I l on which the pot rests. The base containsa heating element 82 and the element is provided with the usual cord i3terminating in a plug it The pot is provided with a cover l6 having avent tube l6 mounted centrally thereof. The tube is opened through thecover and it may be closed by a weight II, which is slipped over the topof the outlet end of the tube when pressure is to be maintained. Thecover seats against an overhanging rim IS on the pot and initially it isheld in place by a lever l9 secured to the vent tube assembly and havinga fulcrum member 20 which rests in a depression inthe top of boss 2|forming part of the pot handle, the lever being provided with a hook 22which may be hooked over the stem of the handle.

Mounted in an opening through the cover between its rim and the venttube is a pressure switch 25; This switch includes a housing 26terminating in a threaded neck 21 which passes through the opening inthe cover and is held in place by nut 28. A passage 29 through the neckleads to a chamber 36 within the housing and closed at its top by adished diaphragm 3| which has a peripheral cylindrical flange anchoredin a groove in the wall of the housing in any suitable way, asbysoldering.

A plate 32 of insulating material is seated on a circumferentialshoulder on the wall of the housing above the diaphragm 3i and thisplate is held in position by a tubular section 33 of insulating materialand a top plate 34 of insulating material, which is held in position byan intumed rim 35 on the housing, A pair of contacts 36 are mounted inopenings in plate 32 and these contacts pass through and areelectrically connected to respective terminal members 31 which extendupwardly along the inner surface of tube 33 and terminate in prongs 38which pass outward from the casing through openings in aaeaow connectthe cooker to a source of power, current may now through the heatingelement and the signal lamp, since diaphragm 3| is in its initialposition with its upper faceconcave. heating progresses, pressure isgenerated within the vessel and builds up until it reaches a value atwhich it acts on the diaphragm and causes the central portion thereof tosnap to a position in which its upper surface is convex. This moveplate34. Prongs' 38 are of the shape and form of the prongs of an ordinaryelectrical plug.

The ends of the contacts 36 lying within the chamber defined by theinsulating members are bridged by a member 39 which is forced intoengagement with the contactsby a spring 40 seated at one end on thememberand at the other in a depression in the inner surface of plate 34.A pin 4| is mounted in an opening of the conductors 43 leading from theterminals in receptacle 42 is connected within the base to oneof theconductors in cord I3 and the other conductor from receptacle 42 isconnected to one end of the heating element l2, the other end of theelement being connected to a conductor in cord 13. The lamp 44 is thenconnected across the terminals 1: the heating element,

In the use 01 the cooker described, the food and the usual smallquantity of water are placed in the pct 10 and the cover is then placedin the top of the pot and held in position by lever I H and hook 22. Thereceptacle 42 is then mounted on prongs 36 of the switch. when theprongs of plug l4 are inserted in a receptacle to ment of the diaphragmcauses pin 4| to raise the bridge member 39 from engagement with con--tacts 36 and the circuit through the heating element and lamp is thenopened and the flow of current is stopped.

member 39 and current to flow again to the heating element. Whenever itis desired to stop the 'heating at any time prior to the operation ofthe switch, the current may be shut off either by disconnecting the plugl4 from its receptacle or removing receptacle 42 from the top of theswitch. With receptacle 42 removed, the cover can be taken off the potand cleaned b washing in the usual way, since water'cannot enter theswitch through the diaphragm or through plate 34.

- In cookers for some uses, it may be desirable to divide the winding ofthe heating element so that only part thereof isunder thecontrol of thepressure switch and connections suitable for the purpose are illustratedin the wiring diagram of Fig. 3. In this arrangement, the heatingelement is divided into two portions, l2a, l2b. Portion 12b is connecteddirectly to power lines 45 r so that current flows through this portionof the winding, whenever the lines 45 are connected to a source ofpower, The part l2a of the winding is connected to one of the lines 45through a circuit 46 containing the pressure switch 25, so that currentmay flow through part l2a only when the pressure within the vessel isbelow the safelimit. 'The pilot lamp 44 is connected across the part l2aof the winding and is lighted only when the entire winding isfunctioning.

From the foregoing, it will be apparent that and compact, its presenceon the cover does not impede the user in the ordinary handling of thecover. The prongs of the switch and the receptacle in which such prongsare received form a quick detachable coupling by which the electricalconductors can be quickly connected or disconnected from the switch, asdesired, and when the conductors are disconnected, the cover may becleaned by immersion in water in the usual way, since the switch iswaterproof.

I claim:

1. In a portable pressure cooker for the quick cooking of foodsincludinga cookin receptacle for the food to be cooked, afluid-and-pressuretight cover secured thereto, and a heating element forheating the receptacle, a relatively small com- Asthe' sooner? switchfor coritrcllin-c. the supply oi current to theheating element includingwaterproof mounted directly upon the cover and sepconnected to thecontacts within the housing and projecting therefrom, a quick detachablecoupling engaging said terminals for connecting the termimale to theheating element and to a source of power, respectively, and meansactuated by said i -acting diaphra m for opening the switch at apredetermined cooking pressure generated within said cooking receptacle.

2, The combination with a pressure cooker hava cooking receptacle, acover therefor, and means for heating the receptacle, of a switchmounted directly upon the cover and including contacts enclosed within awaterproof housing and having terminals accessible from outside thehousing, connections for detachably connecting the terminals to theheating means and a source of power, respectlveLV, and means responsiveto pressure generated within the receptacle for actuating the switch.

3. The combination with a pressure cooker hav ing a. cooking receptacle,a cover therefor, and means ,ior heating the receptacle, of a switchmounted directly upon the cover and including contacts enclosed within awaterproof housing and having terminals projecting outside the houslug,a receptacle in which the terminals are receivable, connections forconnecting the terminals through the receptacle tothe heating means anda source of power, respectively, and means responsive to pressuregenerated within the cooking receptacle for actuating the switch.

4. The combination with a pressure cooker having a cooking receptacle,8. cover therefor, and means for heating the receptacle, of a switchmounted directly upon the cover and including contacts enclosed within awaterproof housing, a coupling which includes terminals connected withinthe housing to the switch contacts and projectin: out o! the housing anda receptacle for receiving the terminals, electrical connections fromthe coupling to the heating means and a source of power, respectively,and means responsive to pressure generated within the cooking receptaclefor actuating the switch.

5. The combination with a pressure cooker having a cooking receptacle, acover therefor, and

' receptacle for actuating the switch.

6. The combination with a pressure cooker having a cooking receptacle, acover therefor, and means for heating the receptacle, of a switchmounted directly upon the cover and including contacts enclosed within awaterprooi'houslng, a coupling which includes terminals connected withinthe housing to the switch contacts and projecting out of the housing anda receptacle for receiving the terminals, electrical connections ironthe coupling to the heating means and a source oi power, respectively,and m sive to pressure within the caching actuating the switch andincluding phragm clcninz, an orifice through 7. The combination with apressure cooker having a coo receptacle, a cover therefor, and means forheating the receptacle, of a switch mounted directly upon the cover andincluding contacts enclosed within a waterpr f h n and having terminalsaccessible iron: outside the housing, connections for detachablyconnecting the terminals to the heating means and a source of power,respectively, and means, including a dished diaphragm exposed topressure generated within the cooking receptacle for actuating theswitch,

a. The combination with a pressure cooker hav ing a cooking receptacle,9, cover therefor, means for heating the receptacle, of a water proofswitch mounted directly upon the cover, connections for connecting theswitch to the heating mean and to a source of power, respectively, aquick detc chable coupling in the connections adjacent lhe switch, andsnap action means responsive to pressure generated within the receptaclefor actuating the switch.

9. The combination with a pressure cooker having a cooking receptacle, acover therefor, and means for heating the receptacle, or a watchproofswitch mounted directly upon the cover, connections for connecting theswitch to the heating means and to a source 02 power, respec= tiveLv, aquick detachable coupling in the connections adjacent the switch, andmeans for ac tuating the switch, including a dished diaphragm aposed topressure generated within the recep- 10. In a pressure cooker whichincludes a cooking receptacle, a cover therefor, and a heating element1'01 heating the receptacle, the combination of a switch controlling thesupp y of current to the heating element and including a housing mounteddirectly on the cover and containing ,a. waterproof chamber, contacts inthe chamber,

a spring-pressed bridge member normally connecting the contacts, adiaphragm within the housing exposed to pressure within the receptacle,an element through which the diaphragm may act to move the member fromthe contacts, and terminals connected within the chamber to the contactsand extending out of the chamber, and an electrical receptacle forreceiving the exposed portions of the terminals and with the latterforming a quick detachable coupling,

11. In a pressure cooker which includes a cooking receptacle, 9. covertherefor, and a heating element for heating the receptacle, a switch forcontrolling the supply of current to the heating element including ahousing adapted to be mounted on the cover and having an inlet passagefrom the cooking receptacle, adiaphragm closing the passage, a.waterproof chamber within the housing, contacts within the chamber,terminals connected within the chamber to the contacts and projectingout of the housing, a springpressed member within the chamber normallyconnecting the contacts, and a pin engaging the diaphragm and operablethereby to free the member from the i'zontactso 12. In a pressure cookerwhich includes a cooking receptacle, a cover therefor, and a heatingelement for heating the receptacle, 3. switch for controlling the supplyoi. current to the heating element, including a housing adapted tomounted on the cover and having a portion extending through an openingin the cover. a passage in said portion, a, diaphragm within the housingclosin the passage. a waterproof chamber within the housin contactswithin the chemoperable by the diaphragm to tree the member from thecontacts.

13. The combination with a pressure cookerhaving a cooking receptacle, acover therefor, and

means for heating the receptacle, 0: a. switch mounted directly upon thecover having snap actin means responsive to pressures generated 'withinthe receptacle for actuating the switch and producing an audible signal,and-detachable connections for coumecting the switch to the heatingmeans. I

14. The combination with a pressure cooker having a cooking receptacle,a cover therefor, and means for heating the receptacle, oi a snap-acting means mounted upon the cover rnsive to pressures generatedwithin the receptacle for producing an audible signal at a predeterminedpressure.

' HARRY A. WILSON.

